It has now extended the trial to create a sliding scale of payments to celebrities, public figures and ordinary users outside the sender's usual network.

Fans wishing to send messages to Olympic diver Tom Daley could be charged £10.68, while those hoping to contact author Salman Rushie could pay £10.08, according to the Sunday Times.

A spokesman for Facebook confirmed the new system was undergoing a trial period, insisting it is aimed at preventing spam.

“The system of paying to message non-friends in their inbox is designed to prevent spam while acknowledging that sometimes you might want to hear from people outside your immediate social circle,” Facebook said in a statement.

“We are testing a number of price points in the UK and other countries to establish the optimal fee that signals importance.”